The challenge in agrochemistry or other large scale field applications of chemicals or active agents such as, for example, pesticides, herbicides, bacteriocides, nematicide and fungicides is to find ways of achieving control of the target organism while limiting the amount of the xenobiotic substance that is loaded into and is free-moving in the ecosystem by leaching or by aerosol drift. The amount of such chemical that is required is a function of their potency, the ability to place the chemical selectively and their susceptibility to removal either via destruction in the environment (metabolism, photolysis, etc.) or loss (leaching, drift). Unfortunately, environmentally desirable properties such as facile biodegradation or other loss may result in a need for frequent re-application and thus an increase in the load on the environment. Although there has been dramatic progress in identifying more potent active agents for use in pest control there has been rather less success in controlling the application or placing of these chemicals in such a way as to limit losses and maximize efficacy.
When a chemical is applied to soil, it does not always stay put. Chemicals follow any number of pathways. They can enter plants, insects, and other living organisms. They can volatilize, which means they change into a gas. They can be broken down by sunlight, microorganisms, or chemical reactions with water, and they can chemically attach to soil and organic particles. They can also remain in a dissolved form, and then leach with water through the soil, sometimes winding up in groundwater. The fate of mobile chemicals, however, can be thought of as a race between the various degradation processes and leaching to groundwater. Leaching is the movement of contaminants, such as water-soluble pesticides or fertilizers, carried by water downward through permeable soils. Generally speaking, most pesticides adsorb to soil particles (especially clay), become immobile, and do not leach. The fate of mobile pesticides, however, can be thought of as a race between the various degradation processes and leaching to groundwater. In contrast to surface water, groundwater does not continually dilute the contaminants that reach it. Flushing a plume of contamination from groundwater may take many years. The cold temperatures, limited microbiological activity, lack of sunlight and low oxygen levels that are found deep beneath the soil surface, slow chemical breakdown. The result is that there is very little, if any, breakdown of chemicals once they reach an aquifer.
As mentioned above, chemicals often do not reach their intended target but are transported to groundwater and surface waters. There is a need in the art for improved retention and release (controlled application) of active agents for agriculture in a manner that reduces loss of actives to leaching. The invention is directed to these, as well as other, important ends.